After 40 years in Alaska, one gun and one gun only. That's easy, 30-06!!!!
You don't waste shells on birds, rabbits, or other small game. That's what traps, snares, and deadfalls are for. 30-06 is good for Moose, Caribou, and Sheep, for food. It's also good for protection against Grizzlies, Brownies, Black Bears, and Wolves.
Now what do I personally carry during the summer. It's a toss-up between a 30-06 Handi, and a .338WM TCR, both are single shots. Depends on my mood when I leave the house.